The museum’s director of education and public programming Clifford Chanin told CBS 2’s Andrea Grymes on Sunday that things are going smoothly on building the museum space.

“The progress on the construction and the development of the exhibition spaces and so on is really now at peak speed and we’re working real hard and looking at an opening of the museum for the whole world next spring,” Chanin told Grymes.

A section of the so-called survivor’s stairs will be on display, along with a red bandana that belonged to a trader who was also a volunteer firefighter. He ran back into the burning South Tower to try to rescue those trapped inside.

Wednesday marks the 12th anniversary of the deadliest terror attack on U.S. soil.